chore: remove vibe-coding artifacts from tracking, sync notes and obsidian config

- Untrack .claude/launch.json (Claude Code config)
- Add .claude/, .mcp.json, CLAUDE.md, and AI-generated CSVs to .gitignore
- Add _notes/ vault (architecture, API, tasks, bugs, infra docs)
- Add .obsidian/ plugin/vault config (workspace state excluded)
- Sync CHANGELOG.md

_notes/02 - Features/Gamification.md

@@ -0,0 +1,29 @@
+# Feature: Gamification
+
+**Module path:** `lib/features/gamification/`
+
+## Overview
+Engagement system using points, rankings, and achievements to reward users.
+
+## Components
+- **EP (Experience Points)** — earned by attending/booking events
+- **RP (Reward Points)** — redeemable rewards currency
+- **Leaderboard** — ranked user standings
+- **Achievements** — milestone badges/unlocks
+
+## Key Files
+| File | Purpose |
+|------|---------|
+| `lib/features/gamification/` | All gamification logic & UI |
+
+## Game Mechanics
+- [ ] Document EP earning rules
+- [ ] Document RP earning rules
+- [ ] Document achievement triggers
+- [ ] Document leaderboard ranking logic
+
+## Notes
+
+## Related
+- [[02 - Features/Events]]
+- [[04 - API & Backend/API Notes]]